Apparatus for reducing turbulence



April 12, 1955 D. VAWTER 2,705,972 APPARATUS FOR REDUCING TURBULENCEFiled Aug. 25, 1952 United States Patent O F APPARATUS FOR REDUCINGTURBULENCE Dale Vawter, Harrison, Wis. Application August 25, 1952,Serial No. 306,216

2 Claims. (Cl. 138-47) The present invention is concerned with anapparatus for reducing turbulence in flowing liquid streamsparticularlywhere the streams are being directed from a higher level to a lowerlevel.

In many industrial processes it is necessary to transfer a flowingliquid stream from a higher level to a lower level and to do so with aminimum amount of turbulence being produced in the liquid stream. A goodexample of this type of process occurs in the paper making industrywhere pulp suspensions must be transferred from various portions of thepaper making assembly, and foaming, agitation, splashing, and turbulenceresulting from the free fall of the liquid suspension in conduits orchannels presents a very distinct problem. In handling such suspensions,it is desirable to have a very low velocity head so that the compositionof the suspension is maintained more uniform, the liquid flow can becontrolled more readily, and the liquid is free of air entrainmentresulting from the turbulence.

In addition to its use in the paper making industry, the apparatus ofthe present invention will find use generally where the problemsofexcessive agitation, splashing, and turbulence are to be controlled.

An object of the present invention is to provide means for minimizing orreducing turbulence in flowing liquid streams.

Another object of the invention is to provide an apparatus fordissipating much of the kinetic energy contained in a flowing stream soas to leave the stream in a quiescent condition.

Still another object of the present invention is to provide an apparatusfor reducing turbulence in a liquid stream and thereby leave said streamwith a relatively low velocity head.

Other objects and features of the present invention will be apparent tothose skilled in the art from the following description of the attachedsheet of drawings which illustrate the preferred embodiment of thisinvention.

Figure 1 is a front elevational view of an assembly for reducingturbulence embodying the principles of the present invention; Figure 2is a side elevational view of the assembly illustrated in Figure 1; andFigure 3 is a cross-sectional view taken substantially along the lineIII-III of Figure 2.

In the form of the invention illustrated in the drawings, the assemblyincludes a generally circular hollow casing which is provided at itsupper end with an inlet generally indicated at numeral 11. A conduit 12introduces the flowing stream through the inlet 11 and into the interiorof the casing 10.

The casing 10 also has centrally located bearing supports 13 and 14 atopposite ends thereof, the bearing supports 13 and 14 receiving a shaft16 for rotation within the casing 10. As best seen in Figure 3, acircular core 17 is secured to the shaft 16 within the casing 10. Aplurality of circumferentially spaced vanes 18 are located in spacedrelation along the periphery of the core 17, or the vanes 18 may beintegral with the core 17. The specific shape or contour of the vanes 18will vary with each installation but in general may include a contouredfoil or scoop portion 18a for minimizing the amount of turbulencecreated by the fluid stream as it strikes the vanes 18. Thecircumferentially spaced vanes 18 and the core 17 thereby provide arotatable impeller whichis acted upon by the flow of liquid through thecasing to dissipate some of the kinetic energy contained in the flowstream originally and developed during the fall of the 2,705,972Patented Apr. 12, 1955 liquid from a higher level to a lower level. Asbest seen in Figure 2, the edges of the vanes 18 extend into closeproximity to the walls of the casing 10 so that little or no liquid isable to flow through the casing without engaging the surface of one ofthe vanes 18.

As the liquid enters the hollow casing through the inlet 11 and fallsthrough the casing, some of the energy originally present as potentialenergy is transformed into kinetic energy in the flowing stream. Inorder that the turbulence of the stream may be minimized and thevelocity head reduced to a sufliciently low value, most of this kineticenergy must be absorbed before the stream passes to the outlet in thecasing. The liquid stream in rotating the impeller consisting of thevanes 18 and the core 17 loses some of its kinetic energy, but for mostpurposes the amount of energy thus dissipated would be insufl'icient toreduce the turbulence to the desired degree. In order to increase theresistance or the work of the impeller, the assembly is provided with abraking means which supplies a predetermined and adjustable brakingtorque on the movement of the impeller. In the form of the inventionillustrated, these braking means take the form of a pair of shoes 19 and20, each of which has complementary recesses through which the shaft 16extends. The brake is fixedly secured to the casing 10 by means of asupport arm 21. The braking torque applied by the brake shoes 19 and 20can be varied by adjustment of a pair of bolts 22 and 23 which determinethe pressure exerted by the brake shoes 19 and 20 on the shaft 16. Theshowing of specific brake means in the drawings is purely by way ofexample, and other means for securing the desired braking torque willsuggest themselves to those skilled in the art.

The liquid stream in passing through the casing and in rotating theimpeller dissipates much of its kinetic energy and the resultingquiescent stream is withdrawn from the casing through an outlet 24 inopen communication with the interior of the casing 10.

As previously mentioned, the assembly of the present invention isparticularly adapted for use in the paper making industry where it isdesired to transfer liquid streams from one level to a lower levelwithout causing an excessive amount of turbulence or agitation. Inoperating the apparatus described, I find it possible to reduce thevelocity heads of a stream to extremely low values on the order of 1 to2 inches of water. Other assemblies for achieving turbulence reduction,such as those employing restrictions of various types in the stream donot operate satisfactorily at low flow velocities and are generallyinefiicient at the range of velocities on which the present apparatus isparticularly effective.

Many modifications can be made to the disclosed apparatus withoutdeparting from the scope of the present invention. It is not myintention to limit the invention to the specific apparatus employed, butonly as necessitated by the scope of the appended claims.

I claim:

1. Apparatus for reducing turbulence in a free falling liquid streamcomprising a casing having a circular chamber, a liquid inlet leadingdownward and tangentially into the chamber, a shaft extending axiallythrough the chamber, a circular core in the chamber carried by androtatable with the shaft, the core being peripherally spaced from andconcentric with the circular wall of the chamber and extending the fullaxial length of the chamber, radial vanes extending from the peripheryof the core the full radial extent between the core and the circularwall of the chamber, said vanes having a width to extend the said axiallength of the chamber, said inlet discharging into the space between thecore periphery and the circular wall, an outlet directed axially of thechamber in the lowest part thereof between the core and the circularwall of the chamber, and means for applying regulated frictionalrotational restraint to the core and vanes during rotation of thelatter, said rotation of the vanes being effected by force applied tothe vanes by liquid entering the chamber through the inlet.

2. The method of reducing turbulence in a stream of liquid flowing froma high level to a low level which comprises eflecting the successiveintroduction of retarding vanes into the stream between said levels,supporting the vanes for movement in a circular path t; which thestrezfin References Cited in the file of this patent is tangent, encosing the vanes on all si es to su stantia y prevent escape of theliquid past said sides as it impinges UNITED STATES PATENTS the vanes,effecting the retarding of the downward move- 165,290 Williams July 6,1875 ment of the vanes under the weight of the liquid imping- 5 600,737Monroe Mar. 15, 1898 ing thereon to pass the liquid off of the vaneswithout 2,544,813 Wall Mar. 13, 1951 turbulence as it reaches the lowerlevel, and diverting the direction of flow of the stream to an outlet,said outlet Q PATENTS providing a path at a substantial angle to theaxis of the 247,718 Great Brltalfl 1926 circular path of the retardingvanes. 10 864,124 France Apr. 19, 1941

